Arrangement for stabilizing trailing vehicle axles

ABSTRACT

A trailing vehicle axle having telescopic piston rods connecting the steering knuckles with the pistons of pneumatic cylinders, the pistons during straight-ahead motion holding the wheels in fixed position subject to the air pressure. In a turn, one piston rod lengthens telescopically without effort and the other enters the cylinder against the air pressure.

United States Patent 91 Schaetf 1541 ARRANGEMENT FOR STABILIZINGTRAILING VEHICLE AXLES [75] Inventor: Friedrich Schaeff,Bensheim-Auerbach, Germany [73] Assignee: Sauer, Otto Achsenfabrik,Keilberg uber Aschaffenburg, Germany [22] Filed: Sept. 9, 1970 [21]Appl. No.: 70,675

' [30] Foreign Application Priority Data Sept. 9, 1969 Germany "P 19 45589.1

[52] US. Cl. ..280/8l A [51 Int. Cl. ..B62d 15/00 [58] Field of Search..280/8l A, 81 R, 80 R, 445, 280/446, DIG. l, 124 F; 188/196; 303/10,

[56] References Cited UNITED STATES PATENTS v 8/1962 Stump et al...280/81 [4 1 Feb. 13, 1973 2,952,474 9/ 1 960 Gouirand .280/812,690,916 10/1954 Gilliam.. ..280/81 2,890,063 6/1959 Stover ..280/813,047,306 7/1962 Easton ..280/81 3,502,003 3/1970 Dobrikin et al...92/101 FOREIGN PATENTS OR APPLICATIONS 446,957 3/1949 Italy ..280/8l692,487 7/1965 Italy ..280/81 Primary ExaminerKenneth H. BettsAtt0rney-Edwin E. Greigg [5 7] ABSTRACT A trailing vehicle axle havingtelescopic piston rods connecting the steering knuckles with the pistonsof pneumatic cylinders, the pistons during straight-ahead motion holdingthe wheels in fixed position subject to the air pressure. In a turn, onepiston rod lengthens telescopically without effort and the other entersthe cylinder against the air pressure.

4 Claims, 6 Drawing Figures PATENTEl] FEB] 3 I975 SHEET 1 OF 3 PATENTEUFEB'I 3191s I SHEET 2 OF 3 PATENT ED FEB] 3191a SHEET 30F 3 ARRANGEMENTFOR STABILIZING TRAILING VEHICLE AXLES' FIELD OF THE INVENTION Theinvention relates to an arrangement for stabilizing the trailing axlesof vehicles including trailers and semi-trailers.

BACKGROUND OF THE INVENTION It is known to provide in a vehiclepneumatically operated stabilizing elements inserted between a fixedpart of an axle and a part thereof participating in turning movements.

The turning movement of such a trailing axle is brought about by lateralforces acting on the wheels.

If the loading and also the roll resistance of both the wheels of theaxle are about the same, the lateral forces are enough to bring aboutcorrect tracking. However, if the wheel loads are unequal, as during aturn, then the can lengthen without effort and the piston is then heldlateral forces, which depend on the loading and the roll resistance ofthe wheels, are also unequal and cause a lateral deviation of the axle.Irregularities in the road surface and imperfect balancing of the wheelsalso cause lateral forces and make the wheels tend to deviate or tooscillate.

In the Published German Pat. application No. 1,811,769, there isdescribed an arrangement for balancing out this type of disturbance bygenerating a force opposing the deviation by means of stirrupshapedlevers acting on the tracking rod of the steering axles or steeringknuckles. There are also stabilizing devices in which one of the partsthat turn relative to each other, such as the part fixed to the vehicle,is provided with a heavy cam and the other part with a pressure member,the cam and the pressure member being held in pressure engagement andexerting an opposing force owing-to a resolution into components at thepoint of pressure. The resolution into components is brought about bythe direction and the force of mutual pressure relative to thecorresponding inclincation of the cam curve, which is dependent on theangle of deviation.

SUMMARY OF THE INVENTION The stabilizing arrangement to be describedbelow is simpler and less costly than the known ones and affords thepossibility of adjusting the trailing axle in a simple manner in normalposition corresponding to straightahead motion.

The arrangement according to the invention is characterized by astabilizing element for each of the turning directions, comprising anair pressure cylinder having a telescoping piston rod, the wheels of theaxle during straight-ahead motion being fixed in neutral position bypressure engagement of the pistons in the terminal position thereof inthecylinders.

The telescoping rod is directly connected to a movable part of the axle.The pivot point of the piston rod and the cylinder being attached tomutually movable parts, the rod must change its position in response toa turning movement. Owing to the telescopic construction, a shorteningof the rod causes the piston to penetrate into the cylinder and there istherefore no effective shortening relative to the length correspondingto straight-ahead motion. 0n the other hand, the rod in terminalposition by the air pressure. Threads are provided on the piston rodsfor adjusting the trailing axle without play. The pressure cylinders maybe conventional pneumatic brake cylinders.

The arrangement of the invention has the advantage of simplicity ofconstruction and of operation.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described in moredetail with reference to embodiments thereof shown on the drawing, whichis on scale and in accordance with standard conventions, so that only abrief description thereof will be necessary.

FIG. 1 is a plan view of a vehicle trailing axle in normal position witha stabilizing arrangement according to the invention.

FIG. 2 is a view corresponding to FIG. I of a bogie tracking deviceincorporating the invention.

FIG. 3 is a lateral view in partial longitudinal section of astabilizing cylinder with its piston rod.

FIG. 4 is a schematic illustration of the stabilizing elements accordingto the invention coupled to a manually operable control valve.

FIG. 5 is a schematic illustration of the stabilizing elements accordingto the invention coupled to a conventional load-controlled levellingvalve for varying the pressure in said stabilizing elements in aload-dependent manner.

FIG. 6 is a schematic illustration of a conventional load-dependent airspring suspension means combined with the stabilizing elements accordingto the invention to vary the pressure in the latter as a function ofload.

DESCRIPTION OF EMBODIMENT In FIG. 1, the housing 12 of the trailing axleof a vehicle extends in the direction of the geometric axis 10, which isalso the axis of rotation of the wheels 14 and 16 when travelingstraight ahead. The outer or terminal sections of axle housing 12 arebent forwardly, as is known per se, and support at 18 and 20 the journallinks for the steering knuckles 22 and 24. Apart from a possible toe-in,the wheels are always parallel to each other, this being assured inwell-known manner with the aid of the cross tie 26. In this arrangement,the axle housing 12 is fixedly attached to the fixed part of thevehicle, i.e. with the chassis. The other parts, such as wheels,steering knuckles and cross tie, participate in the turning or returningmovements. Between the two groups of parts, there is inserted astabilizing device, which in the present instance comprises a pair ofair pressure cylinders 28 and 30 with telescopic rods 32 and 34.

The construction of the stabilizing elements 28, 32 and 30, 34 is shownin FIG. 3. If the wheels turn to the position A of FIG. 1, which refersto the planes of symmetry and of rotation thereof, the distance betweenthe supporting bracket 40 of cylinder 28 and the pivot point 36 betweenrod 32 and steering knuckle 22 must become shorter, and the distancebetween the supporting bracket 42 of cylinder 30 and the pivot point 38between rod 34 and steering knuckle 24 must become longer. The unitcomposed of the pressure cylinder and the telescopic rod is nowconstructed so as to make the lengthening possible without transmissionof a force in the longitudinal direction of the rod, whereas theshortening takes place against the pressure of the cylinder.Accordingly, in comparison with the neutral position corresponding tostraight-ahead traveling, only one of the two cylinders is in operationat any moment.

Cylinder 28 is equal to cylinder 30 and telescopic rod 32 is equal torod 34. The same combination of cylinders and telescopic rods is used inthe bogie arrangement according to FIG. 2 and it is therefore sufficientto describe cylinder 28 and rod 32 of FIG. 1.

Cylinder 28 is a conventional brake cylinder of a pneumatic brakeinstallation. Between the two halves 42 and 44 of the housing, a rubberdiaphragm 48 is tensioned and fixed in position in conventional manner.The outer housing half 42 has a connecting tube 50, through which thepressure side of diaphragm 48 is supplied with air under pressure.Preferably, the air pressure in this space is regulated in accordancewith the existing load conditions so as to be increased in dependence onan increase in wheel loading, in axle loading or in the overall vehicleload. In a vehicle with pneumatic springing, the cylinders of this novelstabilizing device may be advantageously pneumatically connected to thespringing system. There are known pneumatic cushioning systems (usuallydesignated in the art as air suspensions) in which the cushioningbellows of the wheels at one side of the vehicle are pneumaticallyisolated from the cushioning bellows at the other side of the vehicle.In such an arrangement it may be of advantage to have access to a pairof separate stabilizing cylinders, as in the present arrangement, sinceit is then possible to connect each of the stabilizing cylinders withonly one of the pneumatic systems.

The other housing half or section 44 is fixed to a portion of one of thetwo constructional units which are mutually angularly displaced when aturning or returning movement occurs. For instance, in FIG. 1, housingsection 44 is connected to journal bracket 40 and therefore also withaxle 12 by means of bolts 52 shown in H6. 3.

The air pressure in the chamber 54 of the cylinder causes diaphragm 46to be permanently pressed against the bottom of a piston 56, shown herefor simplicity as having a substantially flat shape. The rod 58 of thepiston is telescopically guided in a tube 60. The two parts 58 and 60together form the telescopic rod or pressure rod 32. Rod 32 is pivotallyconnected at 36 by means of a ball joint 62 to steering knuckle 22, asis apparent from FIG. 1. Between joint 62 and tube 60 there is insertedan adjusting device for varying the effective length of the tube. Tothis end, the tube is screwed to a greater or lesser extent onto athread 64 of a joint bolt 66 and held in position by means of a clampingsleeve 68 mounted thereon. The technical details of this adjustmentdevice are of well-known type, as is apparent from the drawing.

The housing portion 44 has an integral annular part 44', the inner wallface of which serves as an abutment for the piston 56 to limit itstravel directed outwardly from the chamber 54. in such a position of thepiston 56 (as shown in solid lines in FIG. 3), the membrane 46 is fullyextended and is, in this condition, rigidly supported by the part 44' ofthe housing portion 44.

Rod 32 extends through a wide aperture 70 into housing section 44.Since, under normal conditions,

points 62 and 52 are not only linearly removed from each other when aturn is entered into, but also an angular movement takes place, it isnecessary for rod 32 to be capable of angular movement relative to theplane of attachment of the diaphragm. To this end, aperture must becorrespondingly wide.

The two rods 32 and 34 are adjusted with the aid of the adjustingdevices such as 64, 66, 68 in such a way that in the neutral positioncorresponding to straightahead travel, the end face 72 of tube 60 justcontacts piston 56 without any play therebetween. If external forcestend to extend the rod-cylinder system, 32, 28, the system followswithout opposing it, because end face 72 moves away from piston 56 andthe piston is held in this position against the air pressure by means ofthe stops or the like referred to above, which are not shown in thedrawing. On the other hand, if the external forces attempt to shortenthe system 28, 32, this is possible only by means of a pressure of endface 72 of tube 60 against piston 56 and against the pressure in chamber54. Under the influence of such external forces, the piston and thediaphragm are pushed into cylinder 28 up to the terminal position shownin dashdot lines in FIG. 3, possibly with more or less of an angularmovement. If the volume of cylinder 28 is closed or if the total volumecommunicating with chamber 54 is not large relative to the volume ofchamber 54, the force required to push piston 56 into the chamberincreases with continuing movement, and the return force is thereforethen dependent on the angular deviation of the wheels in a progressivemanner.

As was pointed out above, the pistons of both cylinders are in theirterminal positions when the vehicle moves straight ahead and they arepushed by the air pressure into contact with the stops provided in thecylinder housing. Upon a turning movement of the axles, the piston ofthe corresponding cylinder is pushed by the push rod into the cylinderagainst the pressure of the air supplied thereto and exerts acorresponding return force on the wheel, at the same time as the othercylinder is passive and exerts no force. The air pressure supplied tothe stabilizing cylinder is controlled in dependence on the loading ofthe wheels by means of pneumatic controls of conventional type. There istherefore always alternatively one or the other cylinder in operationaccording to the direction of the turn, left or right.

As is shown in FIG. 2, a system corresponding to the cylinders and rodsystem 28-34 can also be provided on a bogie. FIG. 2 shows a fifth wheelbogie arrangement of a semi-trailer. Instead of the fifth wheel, such abogie may also have a pivot pair journaling arrangement. In theembodiment shown, numeral designates a ball-bearing mounted fifth wheel,which is affixed to the vehicle chassis and has a l of arms 82 and 84extending symmetrically part of the way to the center of the wheel. Theunderlying wheel supporting the wheel axle is fastened to an auxiliaryframe 86, which also takes part in the turning movements. Fixedlyattached to the auxiliary frame by means of brackets 88 and 90 arepneumatic pressure cylinders 28 and 30 similar to the correspondingcylinders of FIG. 1. As in FIG. 1, the cylinders are connected withtelescopic rods 32 and 34 and the pivot points of these rods at the arms82 and 84 correspond to those of FIG.

l and are similarly designated 36 and 38. The center 92 of the fifthwheel is preferably displaced relative to the geometric axis 94 of theroad wheels and in the case of an axle which trails a fixed axle, thedisplacement should preferably be in the direction of travel.

The operation of the arrangement of FIG. 2 corresponds completely tothat explained in connection with FIG. 1, and does not require furtherexplanation.

As indicated earlier in the specification, the pressure prevailing inthe stabilizing elements 28, 32 and 30, 34, is preferably regulated as afunction of the vehicle load. In FIGS. 4, 5 and 6 there areschematically illustrated three simple examples of such control.

Turning now to FIG. 4, there is illustrated a pneumatic pressure source100 which is in communication with the pneumatic cylinders 28 and 30through a hand-operated valve 101 which is operable to furnish differentpressures to said cylinders under full load, half load or no loadconditions.

In FIG. 5 a pneumatic pressure source 100 is connected to the pneumaticcylinders 28 and 30 through a levelling valve 102 which is adjustedautomatically as a function of the vehicle load. In this manner thepressure in the cylinders 28, 30 is varied automatically in aload-dependent manner.

A further development of the load-dependent automatic pressure controlis illustrated in FIG. 6. A pres- I sure source 100 suppliesconventional air spring suspensions 103a and l03b (one associated witheach vehicle side) with pneumatic pressure in a load-dependent manner byvirtue of respective levelling valves 102a and 102b. The pressure sourceis also connected to the cylinders 28 and 30 through a pressure reducingvalve 104 ensuring a minimum pressure therein. The downstream side ofeach levelling valve 102a, l02b is connectedthrough a shuttle valve 105to the cylinders 28, 30 to cause therein a load-dependent pressurevariation.

That which is claimed is:

1. An arrangement for stabilizing a trailing vehicle axle having, oneach side of the vehicle, (a) stationary parts and (b) moving partsparticipating in the turning movements of the vehicle wheels, comprisinga separate stabilizing element for each of the two turning directions ofsaid axle, each said stabilizing element connecting stationary partswith moving parts and operating opposed to one another, each saidstabilizing element having A. a pneumatic cylinder,

B. means for supplying a fluid pressure medium to said cylinder,

C. a piston disposed in said cylinder and exposed to the pressureprevailing in said cylinder,

D. a piston rod affixed to said piston and formed of at least two partsin telescoping relationship with one another, said piston rod beingbiased outwardly by said pressure and E. abutment means on said pistonrod for determining the maximum collapsed state thereof, said abutmentmeans being individually so adjusted on each piston rod that duringstraight-line travel of the vehicle both piston rods are in said maximumcollapsed state, whereby during a turning movement of said vehiclewheels the piston rod associated with the one turning directionundergoes free telescopic extension, while simultaneously,

the piston rod associated with the other turning direction moves itsassociated piston into its cylinder against the pressure prevailingtherein.

2. An arrangement as defined in claim 1, wherein said pneumatic cylinderincludes A. a housing and B. a diaphragm secured within said housing andextending thereacross to define with a portion of said housing anexpansible chamber in which said pressure prevails, said piston beingaffixed to said diaphragm.

3. Arrangement according to claim 1, comprising means for increasing thepressure supplied to said cylinders in response to an increased loadingof said vehicle.

4. An arrangement as defined in claim 3, wherein said vehicle includesseparate air spring suspension means associated with the two sides ofthe vehicle, the pressure in each air spring being a function of loadconditions, the air spring suspension means associated with one vehicleside being in pneumatic communication with one of said stabilizingelements and the air spring suspension means associated with the othervehicle side being in pneumatic communication with the other of saidstabilizing elements; the pressure prevailing in each stabilizingelement varying in the same sense as the pressure prevailing in theassociated air spring suspension means.

1. An arrangement for stabilizing a trailing vehicle axle having, oneach side of the vehicle, (a) stationary parts and (b) moving partsparticipating in the turning movements of the vehicle wheels, comprisinga separate stabilizing element for each of the two turning directions ofsaid axle, each said stabilizing element connecting stationary partswith moving parts and operating opposed to one another, each saidstabilizing element having A. a pneumatic cylinder, B. means forsupplying a fluid pressure medium to said cylinder, C. a piston disposedin said cylinder and exposed to the pressure prevailing in saidcylinder, D. a piston rod affixed to said piston and formed of at leasttwo parts in telescoping relationship with one another, said piston rodbeing biased outwardly by said pressure and E. abutment means on saidpiston rod for determining the maximum collapsed state thereof, saidabutment means being individually so adjusted on each piston rod thatduring straight-line travel of the vehicle both piston rods are in saidmaximum collapsed state, whereby during a turning movement of saidvehicle wheels the piston rod associated with the one turning directionundergoes free telescopic extension, while simultaneously, the pistonrod associated with the other turning direction moves its associatedpiston into its cylinder against the pressure prevailing therein.
 1. Anarrangement for stabilizing a trailing vehicle axle having, on each sideof the vehicle, (a) stationary parts and (b) moving parts participatingin the turning movements of the vehicle wheels, comprising a separatestabilizing element for each of the two turning directions of said axle,each said stabilizing element connecting stationary parts with movingparts and operating opposed to one another, each said stabilizingelement having A. a pneumatic cylinder, B. means for supplying a fluidpressure medium to said cylinder, C. a piston disposed in said cylinderand exposed to the pressure prevailing in said cylinder, D. a piston rodaffixed to said piston and formed of at least two parts in telescopingrelationship with one another, said piston rod being biased outwardly bysaid pressure and E. abutment means on said piston rod for determiningthe maximum collapsed state thereof, said abutment means beingindividually so adjusted on each piston rod that during straight-linetravel of the vehicle both piston rods are in said maximum collapsedstate, whereby during a turning movement of said vehicle wheels thepiston rod associated with the one turning direction undergoes freetelescopic extension, while simultaneously, the piston rod associatedwith the other turning direction moves its associated piston into itscylinder against the pressure prevailing therein.
 2. An arrangement asdefined in claim 1, wherein said pneumatic cylinder includes A. ahousing and B. a diaphragm secured within said housing and extendingthereacross to define with a portion of said housing an expansiblechamber in which said pressure prevails, said piston being affixed tosaid diaphragm.
 3. Arrangement according to claim 1, comprising meansfor increasing the pressure supplied to said cylinders in response to anincreased loading of said vehicle.